The Narrow Spark (Sinthusa nasaka amba)
When it was discovered back in 1995, it was a new record for Singapore. The early authors' checklists did not include this species as extant in Singapore, although it can be found in Malaysia. The Narrow Spark is moderately rare, and is quite local in distribution, often spotted in a few select localities in the forested nature reserves in Singapore. They often lurk in heavily shaded forest, and is skittish.
The underside of the butterfly resembles a Common Tit. However the Narrow Spark is much smaller and possesses a pair of filamentous white tipped tails. The upperside of the male is a deep rich ultramarine blue. This species has been successfully bred on Eurya acuminata and the detailed documentation can be found here.